WTS: Modified Celestron 8" F5 Newtonian (SOLD)

Post by **VinSnr** » Wed Mar 19, 2008 3:45 pm

The scratches was cause by an accident when I first attempt to remove the primary mirror cell after I get the scope... the whole mirror cell "drop" in and cause the scratches... the primary mirror was ok, but I replace the secondary mirror as the primary mirror cell hit the secondary mirror and cause some crack on the secondary mirror. Lesson 1: Don't assume that the primary mirror cell can't go in the tube even it is bigger than the internal diameter of the tube. Lesson 2: Always remove the secondary mirror first before attempt to remove the primary mirror.

Bro, to remove the primary mirror cell, can't you just remove the screws attaching the cell to the tube at the bottom?

Post by **weixing** » Wed Mar 19, 2008 4:40 pm

Hi,

Bro, to remove the primary mirror cell, can't you just remove the screws attaching the cell to the tube at the bottom?

Yap... I did that. But I think the mirror cell had never been taken out before, so it was attach very tightly against the tube wall. As I attempt to remove the mirror cell with tube standing and point downwards, the whole mirror cell suddenly flip on one axis and the whole mirror cell went down in the tube... I think the mirror cell flip a few times on the way down with the sides contacting the tube wall and make all those scratches. I was quite relief that I saw my own reflection when I look in the tube. Anyway, the steel tube is more flexible than I expected... the tube can deform a bit and become larger than the mirror cell diameter on one axis.

Lesson learn and luckily it was a Newtonian... I can upgrade, repair and replace any parts by myself.

Have a nice day.

wx1985 · Post by **wx1985** » Wed Mar 19, 2008 11:43 pm

Nice scope there. Just wondering if that is a gd scope for a newbie like me?
Is it very difficult to modified it into a dobsonian? Really quite tempted by the price ($400) there. And last question, is this scope really portable? it looks heavy and i dun hav transport.. haha.

Post by **acc** » Thu Mar 20, 2008 8:48 am

weixing wrote:Hi,
As I attempt to remove the mirror cell with tube standing and point downwards, the whole mirror cell suddenly flip on one axis and the whole mirror cell went down in the tube... I think the mirror cell flip a few times on the way down with the sides contacting the tube wall and make all those scratches. I was quite relief that I saw my own reflection when I look in the tube.

You are one lucky guy! Almost fell off my chair reading about ur mirror's little adventure down the tube!

Anyway, this is a great beginner's scope. Fairly light for the aperture, inexpensive, and excellent optics.

wucheeyiun · Post by **wucheeyiun** » Thu Mar 20, 2008 10:07 am

wx1985 wrote:Nice scope there. Just wondering if that is a gd scope for a newbie like me?
Is it very difficult to modified it into a dobsonian? Really quite tempted by the price ($400) there. And last question, is this scope really portable? it looks heavy and i dun hav transport.. haha.

It is a good scope, it will take you into the hobby for a while without having to change your scope frequently as this scope have a fair bit of potential. It is good to start out something heavier and labour in love for the hobby, then your next scope is probably a portable apo.

go get it [smilie=admire.gif]

Post by **weixing** » Thu Mar 20, 2008 10:42 am

Hi,

Nice scope there. Just wondering if that is a gd scope for a newbie like me?

IMHO, all scope are suitable for Newbie... just don't get a too small aperture scope when use in Singapore. This scope is probably the largest aperture with decent optics that S$400 can buy in Singapore. Anyway, Newtonian got one advantage that most other type of scope don't have... you basically can upgrade/repair any parts of the scope by yourself.

Is it very difficult to modified it into a dobsonian?

Should not be difficult to make one... the issue is whether can you make a good one.

Really quite tempted by the price ($400) there.

Please note the S$400 price tag do not include the GSO 2" dual speed crayford focuser, but the original 2" rack and pinion focuser.

And last question, is this scope really portable? it looks heavy and i dun hav transport.. haha.

I also don't have transportation... It's not that heavy (~8kg), but a bit bulky. If you don't need to take bus or mrt to your observation site, it's should be manageable... with a trolley, it's can be transport easily.

You are one lucky guy! Almost fell off my chair reading about ur mirror's little adventure down the tube!

Ha ha ha... I think this accident actually force me to learn more about Newtonian design and telescope making as I was forced to learn how to replace the secondary mirror... I realised that the original secondary mirror was a bit under sized after I learn more, so I upgrade to a better and slightly larger secondary mirror... in fact not as difficult as I thought.

Have a nice day.

Post by **weixing** » Thu Mar 20, 2008 2:47 pm

Hi,
By the way, if you think you might have problem transporting or handling this scope, then don't consider it... It's pointless and waste of money to get a large scope if you don't use it often.... even it's cheap.

Anyway, I got another scope on sale which you might want to take a look. It's the Vixen R135 Newtonian ( http://www.singastro.org/viewtopic.php?t=5830 ) and although it's smaller in aperture and priced slightly higher (but may be still the cheapest 5.3" scope you can find with decent optics) than this 8" Newtonian, it's a very portable and versatile scope. Also, it's very light (<4kg), so you'll be able carry to anywhere easily and finding a suitable low cost mount for this scope is easier.

Have a nice day.

Post by **weixing** » Sun Mar 23, 2008 9:39 pm

Hi,
Sold to a nice Singastroian

Hope they'll enjoyed the scope as much as I do.

Have a nice day.

PS: Here I come, R200SS...